Magnetoacoustic Effects in Longitudinal Fields

Abstract

The absorption of transverse and longitudinal ultrasonic waves has been studied as a function of the magnetic field applied along the direction of propagation in pure tin and lead crystals at liquid-helium temperatures. At low fields, the attenuation of both transverse and longitudinal waves exhibits oscillations approximately periodic in reciprocal field, which are ascribed to electron orbits which execute a periodic motion along the field direction. The attenuation of transverse waves in tin shows regions of rapid decrease with magnetic field, which are interpreted as the absorption edges first predicted by Kjeldaas. In higher fields, the absorption of longitudinal waves appears to saturate at a nonzero value, while that of the transverse waves in tin appears generally still to be decreasing with field at fields of about 10 kG.